Animals IV: Higher Animal Form and Function

the study of tissues

an aggregation of cells

• tightly packed and tightly connected cells
• come from all three germ layers
• simple, stratified, or pseudostratefied
• covers outside of body, internal organs, body cavities
• anchored to connective tissue by a basement membrane
• functions - protection against bacterial invasion, fluid loss, mechanical damage; secretion, excretion, sensory reception, absorption
• ciliary movement sweeps material across the surface of the epithelium
• no direct blood supply; diffusion of gases

one cell layer

composed of multiple layers

consists of one layer, but location of nuclei makes it seem that there are multiple layers

extracellular matrix secreted by epithelial cells that separates these cells from the connective tissue

• single layer of thin or flattened cells
• "leaky"; allow for diffusion of gases across their surfaces or between adjacent cells
• found in capillaries, veins, arteries

• single layer of cube-shaped cells
• carries out secretion and absorption
• found in kidney tubules and various glands

• elongated, column-shaped cells
• nuclei are located near the basement membrane
• involved in absorption
• line the uterus and digestive tract

• composed of many cell layers
• covers the skin and lines the mouth, throat, vagina, anal canal
• includes keratin fibers

• protein fibers
• found in skin cells, nails, hair
• waterproof; protects the skin against microbial invasion and injury

• single layer of cells
• location of the nuclei differ from cell to cell, so the tissue takes on the appearance of multiple cell layers
• line the trachea and respiratory tract

• specialized to secrete substances
• found in most glands; mammary, sweat, endocrine glands

• connects, supports, protects other tissues; fills space, produces blood cells, provides protection, repair damaged tissues
• sparse population of cells inside an extracellular ground substance
• fibers (made of primarily collagen)
• ground substance consists of different noncollagenous proteins, water, salts, metabolites, etc.; vary from fluid to solid
• mesodermal origin
• no direct blood supply; diffusion

• binds epithelia to underlying tissues
• forms the membranes between organs; beneath the skin
• composed of spindle-shaped cells (fibroblasts) that produce the fibers
• some immune cells (macrophages) are present
• made of collagen fibers and elastin fibers

give strength to resist stretching

flexible, allow for some distortion

• stores fat (energy storage), cushions organs and joints, insulates
• found beneath the skin, in abdominal membranes, around the brain, heart, kidneys, and joints
• lipids are stored in a large vacuole, called a fat droplet

• often binds different materials together
• found in tendons, ligaments, whites of the eye, and deep layers of the skin
• composed mostly of strong collagen fibers and relatively few cells

connect muscle to bone

connect bone to bone at joints

• provides support and a framework for various body parts
• retained in the trachea, vertebral column, ears and nose, and ends of some bones; bone typically replaces most cartilage in vertebrates
• chondrocytesare present in small island-like cavities called lacunae
• composed of collagen fibers and a gel-like ground substanct
• does not have a blood supply

• protects vital organ and provides a tough endoskeleton for bones to work against, stores vital ions (calcium and phosphate), main site where blood cells are produced (in the marrow)
• collagen fibers and cells (osteocytes) in a hardened matrix filled with calcium phosphate salts
• fibers help bone to resist tensile forces; matrix resists compression
• strongest connective tissue
• osteocytes are found in lacunae
• arranged in concentric circles (lamellae) around Haversian canals (containing the blood vessels and nerves); small canaliculi (canals) are observed sticking across the lamellae
• osteons are the fundamental unit of bone
• includes osteoblast and osteoclast cells

• uninucleated cells that produce bone
• become mature osteocytes when encased in the bone

large, multinucleated cells that tear down or reabsorb bone

• transports substances and helps maintain homeostasis
• consists of cells in a watery matrix (plasma), erythrocytes, leukocytes, and platelets
• fibers can form if blood clotting is stimulated to form the fibrin blood clot
• proteins include - fibrin[ogen], globulins, albumins

• red blood cells
• contain hemoglobin for oxygen transport
• anucleated when mature
• biconclave - a thin membrane is stretched across the center, making the cell very distortable

• white blood cells
• involved in immune responses
• produces anitobies, toxic chemicals, use phagocytosis

fragments of cells involved in blood clotting

• most abundant type (in terms of weight)
• elongated cells that are capable of contraction upon stimulation
• mesodermal origin
• contain many parallel bundles of microfilaments made of actin and myosin

• voluntary control
• striated
• multinucleated
• large cylindrical cells
• cells (muscle fibers) are grouped into muscle bundles, which are grouped into muscles
• metabolically active; vascularized
• attached to bones by fibrous connective tissue called tendons
• contract and fatigue most rapidly

• cells are long and spindle-shaped
• no striations
• uninucleated
• found in the walls of hollow internal organs
• involuntary control
• contract and fatigue slowly

• found only in the heart
• involuntary control
• adapted to rhythmic contractions
• single nuclus
• striated
• cells are often branched
• cells are connected by intercalated disks; structures help to coordinate contraction
• intermediate in terms of fatigue and contraction speed; cells rest between heartbeats

• found in the brain, spinal cord, and peripheral nerves
• sense external and internal stimuli
• send signals; function in coordinating, regulating, and integrating body activities
• of ectodermal origin
• send action potentials in a unidirectional direction (from presynaptic cells to postsynaptic cells)

glands and muscles

• basic type of nerve cell
• uninucleated
• consist of a soma (cell body), axon (sends), and one or more dendrites (recieves)

supportive cells in nervous tissue